The software itself remains available, though it's unclear whether that will continue to be the case. Popular photo-sharing service 500px was recently removed by Apple from the App Store following issues over nudity, which is not allowed under Apple's App Store Guidelines.

An Apple spokesman declined to comment on the choice.

The change, which was noted earlier by Business Insider, follows controversy over Twitter's Vine app, which facilitates the creation and exploration of short-form videos. The service launched last week (first on Apple's iOS platform with plans for Google's Android) and quickly garnered buzz, followed by controversy after its editors promoted a pornographic video clip. Twitter pulled down the video in question and apologized, calling it a "human error."

Apple's staff recommendations can provide a serious boost to an app's chances in success in the App Store. Anointed apps get front page promotion in iTunes and in the App Store in iOS, drawing more users who discover apps that way. Apple typically cycles through these recommendations on a weekly basis, but can change them at a moment's notice around a new app's release, feature updates, or social relevance. Complicating matters in this situation is that Apple and Twitter are close business partners, with Apple deeply integrating Twitter into its desktop and mobile operating systems.